1. Field of the Invention
The present invention relates to a Positive Temperature Coefficient (PTC) assembly. More particularly, the present invention relates to a PTC assembly, in which protrusions are formed on opposite longitudinal edges of an electrode terminal, PTC elements are held between the protrusions and are in contact with the electrode terminal, an insulating member is attached to an outer surface of the electrode terminal, and a rod cover houses therein the electrode terminal, the PTC elements and the insulating member, such that a simple structure is realized, fabrication costs are reduced, and a hollow space inside the rod cover is minimized, leading to improved heat transfer efficiency from the PTC elements to the rod cover, reduced noise and a slim structure.
2. Description of Related Art
A vehicle is equipped with an air conditioning system for selectively supplying cold and warm air to the inside thereof. In the summer season, an air conditioner is actuated to supply the cold air. In the winter season, a heater is actuated to supply the warm air.
In general, the heater is based on a heating system in which coolant heated by circulation through an engine exchanges heat with air introduced by a fan, so that warmed air is supplied to the inside of the vehicle. This heating system has high energy efficiency because it uses the heat generated from the engine.
However, in the winter season, heating is not available immediately after the engine is started since it takes some time until the engine is heated after being started. As such, the engine often idles for a predetermined time prior to moving the vehicle until the coolant is heated to a temperature suitable for the heating. This idling of the engine causes energy waste and environmental pollution.
In order to prevent this problem, there has been used a method of heating the interior of the vehicle using a separate pre-heater for a predetermined time while the engine is being warmed up. A conventional heater using a heating coil effectively performs the heating due to high heat generation, but has problems such as high fire danger and frequent repair and replacement of parts due to short lifetime of the heating coil.
Thus, a heater using a Positive Temperature Coefficient (PTC) element has recently been developed. This PTC heater has low fire danger, and can guarantee semi-permanent use due to long lifetime.
FIG. 1 is a schematic exploded perspective view illustrating a conventional PTC pre-heater for a vehicle.
As illustrated in FIG. 1, a PTC pre-heater includes PTC rod assemblies 10 each having a PTC element, heat-radiating fin assemblies 20 disposed in parallel on opposite sides of the respective PTC rod assemblies 10, and cathode terminals 30 disposed in parallel between the heat-radiating fin assemblies 20. The PTC pre-heater also includes frames 40 and 50 mounted on opposite outer sides of the coupling block, in which the PTC rod assemblies 10, the heat-radiating fin assemblies 20 and the cathode terminals 30 are coupled to each other. In addition, the PTC pre-heater further includes housings 60 and 70 coupled to opposite longitudinal ends of a coupling block, in which the PTC rod assemblies 10, the heat-radiating fin assemblies 20, the cathode terminals 30 and the frames 40 and 50 are coupled to each other.
As illustrated in FIGS. 2 and 3, a lower rod cover 11 having therein a channel serves as a kind of a container. An insulator 12 is disposed on the bottom of the lower rod cover 11 so as to prevent a short circuit. The insulator 12 is made of a material such as nylon, which is electrically insulating but has good thermal conductivity.
An anode terminal 17 is fixedly coupled on the insulator 12 in a longitudinal direction, and is made of a metal such as carbon steel or aluminum. PTC elements 18 placed on the anode terminal 17 are fixedly coupled to the insulator 12 so as to generate heat when electric power is supplied thereto. Further, an upper rod cover 19 placed on the PTC elements 18 is coupled with the lower rod cover 11. Electric current flows to each cathode terminal 30 through the upper and lower rod covers 11 and 19.
However, a PTC rod assembly having this construction has problems in that many parts are necessarily assembled because the insulator 12 are separately required, in that each part has a complicated shape, making an assembling process difficult, and in that the thickness thereof is increased. Thus, an insulating effect is increased to degrade heat transfer efficiency. Further, the lower rod cover 11 is not in direct contact with the PTC elements 18 from the structural point of view, and air exists between the parts, so that the heat transfer efficiency of the PTC elements is lowered. Due to expansion of internal air caused by heating, the parts are separated from each other, so that the air leaks out when the pre-heater is initially driven, thereby causing noise and lowering performance.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.